Selective Breeding Notes (Artificial Selection)
Let s recap from last time! Natural selection - The process by which individuals that are better adapted to the environment survive and reproduce more successfully than other members of their species These adaptations are incredibly varied, but are caused by nature. Crash Course Natural Selection
Examples: Counter shading in fish But what about when these variations are not caused by nature, but by mankind? Bird beaks
Where we come in Human Intervention
Selective Breeding or Artificial Selection Selective breeding is the process of breeding plants and animals for particular genetic traits. Parent organisms are bred by people to produce the desired traits in the next generation Domestic animals are commonly bred for various traits. Domestic animal: animal that has been tamed and kept by humans for work, food or as a pet. Let s explore a few examples of selective breeding
Selective Breeding - Dogs Dogs are bred for many reasons such as their intelligence, trainability, and good looks Dogs are all the same species, just varieties!
Selective Breeding - Livestock Longhorn Cattle Good trail cattle, lean meat Hereford Cattle Good beef Aryshire Cattle High milk producer
Selective Breeding -Food Crops
How does this work? From one species, in this case, a common wild mustard, people have selective bred plants over generations to provide a variety of different foods
Selective Breeding - Flowers
Selective Breeding - Bees Africanized honey bees high productivity
Selective Breeding Pros and Cons Pros Higher yield in crops Healthier Animals vulnerability to diseases reduced More Nutrition Provided Breeds Out Harmful Traits Variations of Species more breeds Cons Inhibits Evolution can reduce variation Harmful Pathogens maybe new pathogens could arise In Breeding Risks Food sources change such as when breeding plants, other animals may be unable to feed from these new plants
Problems from Selective Breeding undesirable traits Africanized honey bees, known as "killer bees," are hybrids of the African honey bee with various European honey bees - bred for their high productivity accidentally released from an apiary Brazil in 1957 far more aggressive than the European subspecies 500 bee stings are equivalent to a rattlesnake bite
Problems with Selective Breeding undesirable traits Undesirable traits sometimes appear when trying to produce desired traits Common examples: Hip Dysplasia in dogs a disease in which the ball and socket joint is malformed. Purebreds are more prone to this disease than cross-breeds (mutts) Inbreeding encourages negative traits the gene pool is less diverse
Problems in Selective Breeding WHITE GREAT DANES, DEAFNESS AND EYE ANOMALIES DANES PREDOMINATELY WHITE ARE TYPICALLY DEAF AND MAY HAVE VARIOUS EYE ANOMALIES. THE HEALTH ISSUES ARE NOT CONFINED TO SKIN COLOR, APPARENTLY THE GENES FOR COLOR ARE PAIRED WITH OTHER GENES THAT CAUSES THESE DEFECTS.
Dalmatians The urinary tract is a major weakness in Dalmatians, who are prone to forming urinary stones throughout their life. This is because all Dalmatians are born with a defective urinary system that can't break down uric acid, which occurs when dogs digest food. Another problem? About 33% of all Dalmatians (1 of every 3) are born deaf in one or both ears.
Evolutionary history of dogs: Dogs belong to a single species, Canis familiaris, but that species is comprised of about 400 different breeds. Since they are a single species, they can mate and have viable offspring. Recognized dog breeds take generations to establish through selective breeding or artificial selection. Many of the breeds we have today are the result of people's desire to have dogs with specific features that make them suitable for performing particular tasks, such as retrieving, protection, assistance, hunting, and companionship, to name just a few. The process of breeding a new type of dog often involves identifying desired features, finding dogs with those features, then performing a series of matings to produce offspring with the appropriate combination of traits. After a number of generations, a new breed may be established.
Activity Selective Breeding of Dogs You will begin by examining canine features and their functions. Then you will be given a scenario that describes the type of task they need a new breed of dog to perform. Then select two existing breeds that will most likely produce a successful new breed and determine the resulting offspring's characteristics.
"How to Get an American Foxhound and Why" What are your thoughts?
"How to Get an American Foxhound and Why" The American Foxhound is half descended from the English Foxhounds that were brought to America in 1650. The English hounds were crossed with a French hound. The combination breed became an excellent hunter of wild animals. The American Foxhound has great speed and an excellent sense of smell. It can run at high speed for long periods and has a musical bay that is easy to follow. American Foxhounds are still used as hunting dogs today but are also used as companions and watchdogs.
Designing a Dog Breed Describe the features or abilities of dogs for which humans might breed. How do you decide what type of dog you want or need?
Let s make a dog breed! I will put up pictures and we need to identify which traits would match what we are looking for
Which traits? We need a dog to hear a polar bear and then alarm the bear
What did we pick? Pointed ears are good for hearing and a loud bark will travel a longer distance. Long fur will help the dogs stay warmer out in the cold. Which traits are probably not very important? (eye color). Which breeds would probably be best to cross? (Breed 1 and Breed 3)
Physical Traits Physical traits serve a very specific function for dogs. Each of these could play an important role, or have significance for humans when they need a dog to perform a particular function.
Dog Breed Packets Techer will pass out the "Dog Packet." Each group will be trying to artificially select a new dog with certain traits by crossing two existing breeds. Once you have your packets and group: Take out the "Ownership Card (which you will fill in) and the Dog Breeds this contains the breeds your group may use Follow instructions to complete the activity